SIMULTANEOUS ION-EXCLUSION CHROMATOGRAPHY CATION-EXCHANGE CHROMATOGRAPHY WITH CONDUCTIMETRIC DETECTION OF ANIONS AND CATIONS IN ACID-RAIN WATERS

A simple, selective and sensitive method was investigated for simultan eously determining anions (Cl-, NO3-, SO42-) and cations (Na+, NH4+, K +, Mg2+, Ca2+) in acid rain and related environmental waters in centra l Japan. The method involves simultaneous ion-exclusion-cation-exchang e chromatography with conductimetric detection on a polyacrylate weakl y acidic cation-exchange resin column with a weak-acid eluent. With th e weak-acid eluent (tartaric acid) both anions and cations were separa ted simultaneously, based on ion-exclusion and cation-exchange mechani sm. Owing to the presence of H+ ions in the tartaric acid eluent, the detector response was positive for the anions and negative for the cat ions. Using a 5 mM tartaric acid-7.5% methanol-water eluent, good simu ltaneous separation and detection were achieved in about 30 min. The r esults indicated an ionic balance of about 100% between the anions (in cluding HCO3-) and the cations (including H+).